I. Technical Field
The present invention relates to a hearing aid system.
II. Description of the Related Art
JP-A-9-140000 describes a hearing aid system which directs the directionality of a microphone array toward a speaker to clarify sound collected by the microphones. JP-A-8-9490 and JP-A-2004-23180 describe a sound image localization technique in which the rotation angle of the head of a person with headphones is detected by a sensor, such as a digital vibrating gyroscope or a camera, and even when the head of the person with the headphones rotates, a virtual sound image is not moved. JP-A-2006-503526 describes a method for detecting the rotation angle of a head by using a head tracker.
When the sound image localization technique described in JP-A-8-9490 and the hearing aid system described in JP-A-9-140000 are combined, for example, the hearing aid system shown in FIG. 10 can be realized. FIG. 10 is a block diagram showing the configuration of a hearing aid system of the related art. The hearing aid system of the related art shown in FIG. 10 includes an external microphone array 900 and a hearing aid 800.
The hearing aid 800 includes a binaural speaker 801, a virtual sound image rotating section 803, an inverse mapping rule storage section 805, a direction reference setting section 809, a head rotation angle sensor 811, and a direction estimating section 813.
The head rotation angle sensor 811 is constituted by, for example, a digital vibrating gyroscope, and detects the rotation angle of the head of a person who wears the hearing aid system.
The direction reference setting section 809 includes a direction reference setting switch. In the direction reference setting section 809, the person who wears the hearing aid 800 operates the direction reference setting switch to set a reference direction which defines the direction of a virtual sound source or to reset the head rotation angle sensor 811.
The head rotation angle sensor 811 detects the rotation of the head of the person who wears the hearing aid 800.
The direction estimating section 813 integrates the rotation angle detected by the head rotation angle sensor 811 in the opposite direction, and determines the direction of the virtual sound source to be localized as the angle from the reference direction set by the direction reference setting switch.
The inverse mapping rule storage section 805 stores an inverse mapping rule which is used to convert the angle determined by the direction estimating section 813 to a directional sense component.
The virtual sound image rotating section 803 rotates the sound image of speech of a speaker separated by a sound source separating section 902 described below in the direction determined by the direction estimating section 813 with reference to the inverse mapping rule.
The binaural speaker 801 expresses the sound image of the speech of the speaker rotated by the virtual sound image rotating section 803 as acoustic signals for left and right ears and outputs the acoustic signals.
The external microphone array 900 includes a sound source input section 901 and a sound source separating section 902.
The sound source input section 901 has a plurality of microphones arranged in a predetermined arrangement, and introduces sound from the outside in multiple channels.
The sound source separating section 902 directs the directionality of the external microphone array 900 toward the speaker to separate the speech of the speaker. The separated speech of the speaker is transferred to the virtual sound image rotating section 803 described above.
In the above-described hearing aid system of the related art, the inverse mapping rule which is used to convert the angle determined by the direction estimating section 813 to a directional sense component is stored in advance, and the direction of the sound image of the speech of the speaker with respect to the person who wears the hearing aid system can be determined with reference to the inverse mapping rule.